Conventional radiation sensor devices such as infrared (IR) sensors include an infra-red sensing element micro-machined in the active surface of an integrated circuit chip and mounted in a windowed metal cap whose window allows the sensor to be exposed to IR radiation to be sensed. While this approach is satisfactory it is also quite expensive. Conventional integrated circuit packaging employs a lead frame which together with the integrated circuit chip is encapsulated in epoxy, e.g. Sumitomo G700. The lead frame typically includes a paddle supporting the integrated circuit chip and leads for receiving wire bonds for the integrated circuit chip. This is less expensive than the packaging used in conventional radiation sensing devices, but the plastic is generally not transparent to the radiation to be sensed, e.g., infrared and so is unsuitable for use with integrated circuit chips which have radiation sensors.
Attaching a secondary lens to the radiation sensors with integrated circuit chips discussed above could improve the optical characteristics and effectiveness of the radiation sensor. However, such a design would need to ensure the secondary lens does not protrude above the surface of the encapsulant because it could easily be damaged by automated robotic equipment which places and removes the radiation sensor devices to and from trays used for shipping.